A conventional two-way radio communication system, such as a paging system, typically has an infrastructure including a plurality of outbound transmitters coupled to a radio frequency controller for encoding, batching, and scheduling the transmission of messages to be sent over the air to portable messaging units (PMUs) via an outbound, or forward, communication channel. The PMUs transmit inbound messages over an inbound, or reverse, communication channel. The inbound messages, often referred to as packets, are received by at least one of a plurality of base receivers that are also part of the infrastructure and that are coupled to the controller.
According to some two-way protocols, such as Motorola's ReFLEX.TM. and InFLEXion.TM. protocols, some inbound communications, e.g., message acknowledgments, can be scheduled by the controller. Other inbound communications, e.g., PMU registration in a new area, are unscheduled. The unscheduled, or slotted, inbound communications are referred to as ALOHAs and generally comprise transmissions initiated by the PMUs. The reverse channel is divided into time slots allocated between scheduled communications and ALOHAs. The boundary between the scheduled communications and the ALOHAs can be difficult to estimate, however, because ALOHA throughput is very sensitive to parameters such as the number of base receivers, the distribution of base receivers, the traffic load, and the distribution of PMUs.
Thus, what is needed is a method and apparatus for better managing traffic on an inbound communication channel in a two-way radio communication system.